The purpose of the invention is to measure the bearing (azimuth), or direction, of transient objects against a static background. The transient objects are detected on the basis of reflected sunlight, radiated infrared, shadows, self illumination (e.g. headlights), lasers, or some other change in the static background caused by the transient object.
In general the prior art is limited to optical trackers which generally include sensors mounted on a gimballed platform, or the like, driven by an output signal from the sensors so that the sensors are continously pointed at the target, or solar collectors which include a relatively large array of sensors that do not change position or in any way indicate the direction of a target. The optical trackers are relatively complicated and expensive to construct and operate. The solar collectors do not provide directional information.